High Coronal Electron Densities in a Solar Flare from Fe XXI and Fe XXII X-Ray Line Measurements
Abstract
New calculations of the intensities of the Fe XXI 2p2-2p4l X-ray lines using the distorted wave method are described and compared with observations made by a crystal spectrometer on the Solar Maximum Mission about 6 minutes after the peak of a very intense flare. The comparison enables the electron density of the flare to be derived, the value being about 2 or 3 × 1012 cm-3. Some nearby Fe XXII X-ray lines, scanned 1 minute after flare peak, give an even higher value, 1013 cm-3. This is the first time corroborated values of such high densities have been obtained from ions emitted at temperatures as high as ∼10 MK. They imply very rapid radiation cooling rates and have other important consequences for flare models.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1996
- DOI:
- 10.1086/177531
- Bibcode:
- 1996ApJ...466..549P
- Keywords:
-
- ATOMIC PROCESSES;
- SUN: FLARES;
- SUN: X-RAYS;
- GAMMA RAYS;
- SUN: CORONA